Re: [PATCH] kexec/ppc: Fix kernel program entry point while changing the load addr
On Mon, Mar 04, 2013 at 11:26:24AM +0530, Suzuki K. Poulose wrote: > On 03/04/2013 07:11 AM, Simon Horman wrote: > >[ Cc: linuxppc-dev@lists.ozlabs.org ] > > > >On Sun, Mar 03, 2013 at 01:06:00PM +0530, Suzuki K. Poulose wrote: > >>From: Suzuki K. Poulose > >> > >>uImage probe fills the entry point (ep) based on the load_addr > >>from the uImage headers. If we change the load_addr, we should > >>accordingly update the entry point. > >> > >>For ELF, calculate the offset of e_entry from the virtual start > >>address and add it to the physical start address to find the > >>physical address of kernel entry. > >> > >>i.e, > >> pa (e_entry) = pa(phdr[0].p_vaddr) + (e_entry - phdr[0].p_vaddr) > >>= kernel_addr + (e_entry - phdr[0].p_vaddr) > > > >Would it be possible for someone to provide a review of this change? > To make it bit more clear : > > The entry point of the kernel is usually at 0 offset from the first > PT_LOAD section. The current code makes this assumption and uses the > pa(phdr[0].p_vaddr) as the kernel entry. > > But this *may* not be true always, in such a case the kexec would fail. > While I fixed the uImage case, I thought it would be better to > handle the same case in ELF. > > Btw, this calculation is not specific to ppc32. Thanks, I have applied the patch. ___ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
Re: [PATCH] kexec/ppc: Fix kernel program entry point while changing the load addr
On 03/04/2013 07:11 AM, Simon Horman wrote:
[ Cc: linuxppc-dev@lists.ozlabs.org ]
On Sun, Mar 03, 2013 at 01:06:00PM +0530, Suzuki K. Poulose wrote:
From: Suzuki K. Poulose
uImage probe fills the entry point (ep) based on the load_addr
from the uImage headers. If we change the load_addr, we should
accordingly update the entry point.
For ELF, calculate the offset of e_entry from the virtual start
address and add it to the physical start address to find the
physical address of kernel entry.
i.e,
pa (e_entry) = pa(phdr[0].p_vaddr) + (e_entry - phdr[0].p_vaddr)
= kernel_addr + (e_entry - phdr[0].p_vaddr)
Would it be possible for someone to provide a review of this change?
To make it bit more clear :
The entry point of the kernel is usually at 0 offset from the first
PT_LOAD section. The current code makes this assumption and uses the
pa(phdr[0].p_vaddr) as the kernel entry.
But this *may* not be true always, in such a case the kexec would fail.
While I fixed the uImage case, I thought it would be better to handle
the same case in ELF.
Btw, this calculation is not specific to ppc32.
Thanks
Suzuki
Signed-off-by: Suzuki K. Poulose
Cc: Sebastian Andrzej Siewior
Cc: Matthew McClintock
---
kexec/arch/ppc/kexec-elf-ppc.c| 12
kexec/arch/ppc/kexec-uImage-ppc.c |6 +-
2 files changed, 13 insertions(+), 5 deletions(-)
diff --git a/kexec/arch/ppc/kexec-elf-ppc.c b/kexec/arch/ppc/kexec-elf-ppc.c
index 8e408cc..5f63a64 100644
--- a/kexec/arch/ppc/kexec-elf-ppc.c
+++ b/kexec/arch/ppc/kexec-elf-ppc.c
@@ -397,10 +397,14 @@ int elf_ppc_load(int argc, char **argv, const char
*buf, off_t len,
die("Error device tree not loadded to address it was expecting to be
loaded too!\n");
}
- /* set various variables for the purgatory ehdr.e_entry is a
-* virtual address, we can use kernel_addr which
-* should be the physical start address of the kernel */
- addr = kernel_addr;
+ /*
+* set various variables for the purgatory.
+* ehdr.e_entry is a virtual address. we know physical start
+* address of the kernel (kernel_addr). Find the offset of
+* e_entry from the virtual start address(e_phdr[0].p_vaddr)
+* and calculate the actual physical address of the 'kernel entry'.
+*/
+ addr = kernel_addr + (ehdr.e_entry - ehdr.e_phdr[0].p_vaddr);
elf_rel_set_symbol(&info->rhdr, "kernel", &addr, sizeof(addr));
addr = dtb_addr;
diff --git a/kexec/arch/ppc/kexec-uImage-ppc.c
b/kexec/arch/ppc/kexec-uImage-ppc.c
index e0bc7bb..900cd16 100644
--- a/kexec/arch/ppc/kexec-uImage-ppc.c
+++ b/kexec/arch/ppc/kexec-uImage-ppc.c
@@ -159,15 +159,19 @@ static int ppc_load_bare_bits(int argc, char **argv,
const char *buf,
/*
* If the provided load_addr cannot be allocated, find a new
-* area.
+* area. Rebase the entry point based on the new load_addr.
*/
if (!valid_memory_range(info, load_addr, load_addr + (len + _1MiB))) {
+ int ep_offset = ep - load_addr;
+
load_addr = locate_hole(info, len + _1MiB, 0, 0, max_addr, 1);
if (load_addr == ULONG_MAX) {
printf("Can't allocate memory for kernel of len %ld\n",
len + _1MiB);
return -1;
}
+
+ ep = load_addr + ep_offset;
}
add_segment(info, buf, len, load_addr, len + _1MiB);
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Re: [PATCH] kexec/ppc: Fix kernel program entry point while changing the load addr
[ Cc: linuxppc-dev@lists.ozlabs.org ]
On Sun, Mar 03, 2013 at 01:06:00PM +0530, Suzuki K. Poulose wrote:
> From: Suzuki K. Poulose
>
> uImage probe fills the entry point (ep) based on the load_addr
> from the uImage headers. If we change the load_addr, we should
> accordingly update the entry point.
>
> For ELF, calculate the offset of e_entry from the virtual start
> address and add it to the physical start address to find the
> physical address of kernel entry.
>
> i.e,
> pa (e_entry) = pa(phdr[0].p_vaddr) + (e_entry - phdr[0].p_vaddr)
>= kernel_addr + (e_entry - phdr[0].p_vaddr)
Would it be possible for someone to provide a review of this change?
>
> Signed-off-by: Suzuki K. Poulose
> Cc: Sebastian Andrzej Siewior
> Cc: Matthew McClintock
> ---
> kexec/arch/ppc/kexec-elf-ppc.c| 12
> kexec/arch/ppc/kexec-uImage-ppc.c |6 +-
> 2 files changed, 13 insertions(+), 5 deletions(-)
>
> diff --git a/kexec/arch/ppc/kexec-elf-ppc.c b/kexec/arch/ppc/kexec-elf-ppc.c
> index 8e408cc..5f63a64 100644
> --- a/kexec/arch/ppc/kexec-elf-ppc.c
> +++ b/kexec/arch/ppc/kexec-elf-ppc.c
> @@ -397,10 +397,14 @@ int elf_ppc_load(int argc, char **argv, const char
> *buf, off_t len,
> die("Error device tree not loadded to address it was expecting
> to be loaded too!\n");
> }
>
> - /* set various variables for the purgatory ehdr.e_entry is a
> - * virtual address, we can use kernel_addr which
> - * should be the physical start address of the kernel */
> - addr = kernel_addr;
> + /*
> + * set various variables for the purgatory.
> + * ehdr.e_entry is a virtual address. we know physical start
> + * address of the kernel (kernel_addr). Find the offset of
> + * e_entry from the virtual start address(e_phdr[0].p_vaddr)
> + * and calculate the actual physical address of the 'kernel entry'.
> + */
> + addr = kernel_addr + (ehdr.e_entry - ehdr.e_phdr[0].p_vaddr);
> elf_rel_set_symbol(&info->rhdr, "kernel", &addr, sizeof(addr));
>
> addr = dtb_addr;
> diff --git a/kexec/arch/ppc/kexec-uImage-ppc.c
> b/kexec/arch/ppc/kexec-uImage-ppc.c
> index e0bc7bb..900cd16 100644
> --- a/kexec/arch/ppc/kexec-uImage-ppc.c
> +++ b/kexec/arch/ppc/kexec-uImage-ppc.c
> @@ -159,15 +159,19 @@ static int ppc_load_bare_bits(int argc, char **argv,
> const char *buf,
>
> /*
>* If the provided load_addr cannot be allocated, find a new
> - * area.
> + * area. Rebase the entry point based on the new load_addr.
>*/
> if (!valid_memory_range(info, load_addr, load_addr + (len + _1MiB))) {
> + int ep_offset = ep - load_addr;
> +
> load_addr = locate_hole(info, len + _1MiB, 0, 0, max_addr, 1);
> if (load_addr == ULONG_MAX) {
> printf("Can't allocate memory for kernel of len %ld\n",
> len + _1MiB);
> return -1;
> }
> +
> + ep = load_addr + ep_offset;
> }
>
> add_segment(info, buf, len, load_addr, len + _1MiB);
>
>
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>
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